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Th400/Sm465/Np205

Discussion in 'The Garage' started by Aquaman, Nov 16, 2004.

  1. Aquaman

    Aquaman 1/2 ton status

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    Contemplating this swap. Seems as though it would not cost me all that much to do, but (of course) I always forget the vitals. What this would involve is finding a 4wd Th400, making an adapter (rear of th400 to front of sm465), and having a custom shaft machined for the th400 output, and sm465 input. Then it would be a matter of hooking up shifters and such. Would this be all as far as installation?

    Would it really work very well? I sort of wonder whether the sm465 would be able to handle all the torque from the th400 reduction. But some people go with sm465/sm465 set-ups, so why not?

    What are ya'll's thoughts on this subject? I think I can do this... /forums/images/graemlins/waytogo.gif
     
  2. diesel4me

    diesel4me 1 ton status Premium Member

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    I've seen several home built tractors using two tranny's in a row,but both tranny's were standards(not that it would make much difference)but a few of them broke the input shaft off the second tranny--seems the tourque of an engine is all they were designed for(about 400ft lbs).Once you run that 400ft lbs thru the first tranny in first gear,you multiply it many times--a SM465 has 6.54 to 1 in low gear,so if you had 400 ft lbs it would be mutiplied 6.54 times that,making in the vicinity of 2500 ft lbs!going into the front of the second tranny--thats why a lot of them break,simply too much tourque overload. I think you would need a huge tranny for the second one,like a big rig diesel one that could handle the tourque--it would be very heavy and cumbersome though.It would be neat to put the Th400 in drive and select your crawling range with the rear tranny though!--3 speeds in every range,including reverse--and if you put both tranny's in reverse,it goes foreward at VERY low speed!.The rear axle probably wont like all this tourque either though--might need a huge rear axle to go with all that tourque,like one from a big bus or farm tractor.It would be neat if you can make it durable enough to last--most of the tractors I saw used 10 wheel dump truck 2 speed axles ,and the same trucks tranny for the second tranny,they held up ok..but they weighed a lot!. /forums/images/graemlins/crazy.gif
     
  3. Aquaman

    Aquaman 1/2 ton status

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    It would most likely require 1410 U-joints, which in turn would let me do a square tube shaft conversion (easy). Might be able to keep the strong 4.56 gears I already have, rather than going with 5.38's. I don't know. I am still planning that stage in the build. I need to get it wheeling ASAP. Collecting more parts every week.
     
  4. dhdescender

    dhdescender 1/2 ton status

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    If you could get something he size of a 32 input on the SM465 t might hold up. The tiny ten spline that indexes into the clutch is just too small to take the torque multiplication.

    You going to run a clutch, or just match the RPM's?
     
  5. burbBoy

    burbBoy 1/2 ton status

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    The input shaft will break in time. I ran the 465/465/205 for a while tile the input shaft sheared off. My original plan was just as yours but i didnt have a good TH400 around. You would need no clutch if you just use the 465 as a reduction box. Picking a gear and then leaving it until stopped.

    As for a shifter...all i did is cut one down to use on my second tranny.

    Keep us posted on your progress if you decide to go ahead with it.
     
  6. dhdescender

    dhdescender 1/2 ton status

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    If somone went out of their way to make a custom inpout shaft 32 spline female, (you'd need new retainers and bor ethe case), it *might*, I say *might* hold up.

    You'd probably start eating the internals of the 465 for lunch. 32 spline would be key, as you could bolt a 465 behind another 465 or a TH400. I think you'd survive behind a TH400, as the most multiplication you'd get is 2.5:1 first gear. That said, there is a toruqe converter too.

    Or a 465/420 if you really want a short driveline.

    I would estimate that the custom shafts alone for the swap would be $500 or more, and thats doing decent QTY's.
     
  7. Aquaman

    Aquaman 1/2 ton status

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    I think I'm going to scrap this one. I'll just find a way to clock my current 205, and put a divorced 205 behind it I guess.
     

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